1. Field of the Invention
Example embodiments of the present invention relate to a cyclic compound, a photoresist composition including the cyclic compound, and a method of forming a pattern using the photoresist composition. More particularly, example embodiments of the present invention relate to a cyclic compound having a polycyclic structure, a photoresist composition including the cyclic compound, and a method of forming a photoresist pattern using the photoresist composition.
A claim of priority under 35 U.S.C. § 119 is made to Korean Patent Application No. 2005-123628, filed on Dec. 15, 2005, the contents of which are herein incorporated by reference in their entireties for all purpose.
2. Description of the Related Art
Photolithography is an integral process in the fabrication of semiconductor devices. Part of that process involves the formation of an etching mask by patterning a layer of photoresist composition to define a photoresist pattern. In the case of a chemically amplified photoresist, the composition is typically prepared by mixing a polymer having an acid-labile group, a photoacid generator and a solvent. The photoresist composition exhibits variable solubility in a developing solution depending on its exposure to light. The patterning process generally includes the sequentially executed steps of coating a substrate (or layer) with a photoresist composition to form a photoresist film, partially exposing the photoresist film to light, and developing (removing) the exposed portions of the photoresist film in a developing solution.
The photoresist composition conventionally includes a polymer having a high molecular weight. However, the relatively large molecular size of conventional photoresist polymers can make it difficult to realize further reductions in line widths of photoresist patterns. Also, the molecular weight and molecular size can vary in conventional photoresist polymers, and such polymers are characterized by entangled polymer structures. When the photoresist is developed, molecules of the polymer swell in size in the developing solution, and do not dissolve at a constant rate in the developing solution. This adversely impacts the resolution and line width roughness of the photoresist pattern.
Assume, for example, that the line edge roughness resulting from the use of a conventional photoresist composition is 20 nm on each side of line pattern. For semiconductor devices fabricated with 240 nm line width dimensions, the line width roughness is about 16% of the line width. Recently, however, semiconductor devices having 90 nm line width dimensions are being developed, and the line width roughness of such devices becomes roughly 22% of the line width. For semiconductor devices having 70 nm line width dimensions, the line width roughness becomes about 29% of the line width. It can thus be seen that line edge roughness is an impediment to reducing line width dimensions of semiconductor devices.